Wang Xuan, Zhang Nan, Kou Hui-Zhong
Engineering Research Center of Advanced Rare Earth Materials (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing 100084, P. R. China.
Dalton Trans. 2024 Oct 15;53(40):16592-16597. doi: 10.1039/d4dt00904e.
Multifunctional magnetic materials have broad application prospects in molecular switches and information storage. In this study, four mononuclear Fe(II) complexes are synthesized using a series of pyrenylhydrazone ligands HL. Two deprotonated ligands are coordinated to the iron(II) ions in an enolic form, leading to neutral complexes Fe(L)· with a FeNO octahedral coordination environment. Magnetic measurements suggest that complex Fe(L)·2ACE (1·2ACE, ACE = acetone) is mainly low spin below 300 K and complex Fe(L)·ACE (3·ACE) is high spin, whereas complexes Fe(L) (2) and Fe(L)·6HO (4·6H2O) exhibit gradual spin crossover behavior. The spin states of complexes 1-4 are confirmed by single-crystal X-ray diffraction analysis. The substituent effect on the magnetic properties of the complexes is significant in this system. Temperature-dependent fluorescence emission spectra show the coexistence but no coupling effect of spin crossover and fluorescence for complexes 2 and 4·6H2O.
多功能磁性材料在分子开关和信息存储方面具有广阔的应用前景。在本研究中，使用一系列芘基腙配体HL合成了四种单核铁（II）配合物。两个去质子化的配体以烯醇形式与铁（II）离子配位，形成具有FeNO八面体配位环境的中性配合物Fe（L）·。磁性测量表明，配合物Fe（L）·2ACE（1·2ACE，ACE =丙酮）在300 K以下主要为低自旋，配合物Fe（L）·ACE（3·ACE）为高自旋，而配合物Fe（L）（2）和Fe（L）·6HO（4·6H2O）表现出逐渐的自旋交叉行为。配合物1-4的自旋态通过单晶X射线衍射分析得到证实。在该体系中，取代基对配合物磁性的影响显著。温度依赖的荧光发射光谱表明，配合物2和4·6H2O的自旋交叉和荧光共存但无耦合效应。
